1. Field of the Invention
This invention relates to suspension systems for trailers and, in particular, to a suspension system that incorporates a Watt""s linkage to restrict movement of the trailer axles in a fore-aft direction (i.e., in the direction of vehicle travel perpendicular to the longitudinal axis of the trailer axles).
2. Disclosure of Related Art
In a conventional leading or trailing arm trailer suspension system, a leading or trailing arm, respectively, extends from the trailer frame for connection with the trailer axle. The arm is pivotally connected at one end to the trailer frame and is connected at a second end to the trailer axle. The arm may extend over or under the trailer axle and may support and air spring thereon.
The conventional trailer suspension systems described above have suffered from a significant drawback. These suspension systems are subject to a relatively high degree of movement in the fore-aft direction (i.e., in the direction of vehicle travel perpendicular to the longitudinal axis of the trailer axles). As a result, the welded connections on the trailer axles are weakened and often fail. Further, the stress placed on the welded connections often extends to the axle itself, resulting in a weakening or failure of the axle.
Conventional trailer suspension systems also suffer from another drawback. The leading or trailing arm is generally connected to the axle using a bracket, clamp or other axle connector. This connector must be secured to the axle to prevent movement of the connector relative to the trailer axle. In conventional systems, the connector is secured to the axle by welding the connector to the axle or by using an adhesive. Each of these methods is disadvantageous because each method requires a relatively large amount of assembly time and may result in a weakening of the axle.
There is thus a need for an improved suspension system that will minimize or eliminate one or more of the above-mentioned deficiencies.
The present invention provides a suspension system for supporting a trailer frame on a trailer axle.
A suspension system in accordance with the present invention includes a connector disposed about a trailer axle. The connector may include first and second members disposed about first and second portions of the trailer axle and one or more fasteners that couple the first and second members together. The suspension system also includes an upper arm that is coupled to the frame and to the connector at a point between the frame and the trailer axle. Finally, the suspension system includes a lower arm that is coupled to the frame and to the connector at a point between the trailer axle and the ground. The positional relationship of the upper and lower arms may be described with reference to a pair of planes intersecting the longitudinal axis of the trailer axle. The first plane is parallel to the direction of vehicle travel and to the longitudinal rails of the trailer frame and the second plane is perpendicular to the longitudinal rails of the trailer frame. The upper arm is coupled to the connector on a first side of the first plane (xe2x80x9cabovexe2x80x9d the axis of the trailer axle relative to ground) and to the trailer frame on a first side of the second plane. The lower arm is coupled to the connector on a second side of the first plane (xe2x80x9cbelowxe2x80x9d the axis of the trailer axle relative to ground) and to the trailer frame on a second side of the second plane. The upper and lower arms together form a Watt""s linkage that minimizes and/or eliminates movement in the fore-aft direction (i.e., in the direction of vehicle travel perpendicular to longitudinal axis of the trailer axle) while allowing vertical displacement of the trailer axle.
A suspension system in accordance with the present invention represents a significant improvement over the prior art. The use of a Watt""s linkage minimizes and/or eliminates movement in the fore-aft direction. As a result, the stress on welded connections along the trailer axles is significantly reduced as well as the stress on the axle itself thereby increasing the life of the axle and suspension system and reducing maintenance and repair costs. The construction of the connector of the inventive suspension system also represents a significant improvement over the prior art. In particular, the connector requires less assembly time than conventional connectors and minimizes the potential for damage to the axle.